Catelan A1, Mainardi Mdo C, Soares GP, de Lima AF, Ambrosano GM, Lima DA, Marchi GM, Aguiar FH.
Author information:
1Department of Restorative Dentistry.
Abstract
OBJECTIVE:
To evaluate the degree of conversion (DC) of two light-cured composites with different protocols of light curing.
MATERIALS AND METHODS:
One hundred and ninety two specimens (n = 8) were prepared (5 mm × 2 mm) according to experimental groups: two composite resins (Filtek Supreme and four seasons); three light curing protocols [20 s with the tip of the light curing unit (LCU) device touching composite surface (C); 20 s with the tip of the LCU at 8 mm distant from composite surface (D); and tip of the LCU at 8 mm distant from composite surface and polymerization time required to obtain a radiant exposure of 16 J/cm(2) (DS)]. Four LCUs (Bluephase 16i, Ultralume LED 5, XL 3000 and Optilux 501C) were used. DC of the bottom and top surface of specimens were measured using a FTIR spectrometer. Data were statistically analyzed by 3-way split splot ANOVA and Tukey’s test (alpha = 0.05).
RESULTS:
The results showed that DC of the top surface was higher than the bottom at all experimental conditions (p < 0.0001). Overall, the curing at 8 mm of distance did not affect conversion rate on the top surface (p > 0.05), but bottom surfaces showed DC reduction (p < 0.05). The highest monomer conversion values were observed for C and DS situations.
CONCLUSION:
The distance between the LCU and material surface and radiant exposure can affect the DC. Polymerization at distance should be performed with curing units with higher light power and/or extended exposure time.
PMID: 24856190 [PubMed – indexed for MEDLINE] 1. Acta Odontol Scand. 2014 Nov;72(8):898-902. doi: 10.3109/00016357.2014.920108. Epub 2014 May 26.